Due to its excellent biocompatibility, biostability and physical properties, polyurethane or polyurethane-containing polymers have been used to fabricate a large number of implantable devices, including pacemaker leads, artificial hearts, heart valves, stent coverings, artificial tendons, arteries and veins. Formulations for delivery of active agents using polyurethane implantable devices, however, require a liquid medium or carrier for the diffusion of the drug at a zero order rate.